Question

A solenoid coil 10cm long has 40 turns cm-1. The current rises from zero to its maximum value of 5.0000 A and 0000.01s when the switch is closed. Find the energy stored in magnetic field if the area of cross section of solenoid be 28 centimeter square.

Answer 1

Answer:

Explanation:

Energy stored in a solenoid per unit volume = B₀² / (2μ₀)

B₀= μ₀ n I₀

n is no of turns per unit length .

Energy stored in a solenoid per unit volume = ( μ₀ n I₀)² / (2μ₀)

=μ₀n²I₀²/2

n = 40 turns / cm = 40 x 100 turns per meter.

I₀ = 5000A .

Putting the values

Energy stored in a solenoid per unit volume

= 4π x 10⁻⁷ x 40 x 10² x 5000² /2

= 1256 J/ m³

Volume of solenoid = cross sectional area  x length

= 28 x 10⁻⁴ x .10 = 2.8 x 10⁻⁴ m³

Total energy stored = 1256  J / m³ x 2.8 x 10⁻⁴ m³

= .35 J .